1. Field of the Invention
The present invention relates to a technique for generating a display list.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2012-86450 discusses an apparatus for generating from page description language (PDL) data intermediate data called a display list (DL) that can be processed by a rendering unit. In this apparatus, a PDL interpretation unit interprets PDL data and a DL generation unit generates a DL from a result of the interpretation. Next, the rendering unit executes a rendering operation on the basis of the generated DL to generate a bitmap image.
Hereinafter, a case as illustrated in FIG. 9 where an interpretation result storage unit used for sending a PDL data interpretation result to a DL generation unit has a very small storage capacity will be considered. For example, an interpretation result storage unit will be considered which may have a storage capacity that can only store the interpretation result of one PDL command included in PDL data.
In this case, it is required that, while the DL generation unit is accessing the interpretation result storage unit and is generating a DL from the interpretation result of a single command, the content of the interpretation result is not changed. Thus, while the DL generation unit is accessing the interpretation result storage unit, the PDL interpretation unit does not access the interpretation result storage unit. As a result, while the DL generation unit is accessing the interpretation result storage unit, the PDL interpretation unit does not access this interpretation result storage unit. More specifically, the PDL interpretation unit cannot overwrite the current interpretation result with an interpretation result of the next PDL command in the interpretation result storage unit. Namely, since the PDL interpretation unit and the DL generation unit execute the processing in synchronization with each other, delay in the processing by the DL generation unit directly results in delay in the processing by the PDL interpretation unit.